Plant and process for obtaining clear must from grapes and for vinification

ABSTRACT

A plant is described for obtaining clear must from grapes including at least one centrifugal separator device with horizontal axis that is arranged to carry out a first separating operation, through application of a centrifugal force, between the liquid phase or must and the solid phase from the grape berries in solid state, and at least one tank for settling and/or flotation, either spontaneous or possibly promoted through injection of gas, said tank for settling and/or flotation being arranged downstream of the centrifugal separator device with horizontal axis, said tank for settling and/or flotation being configured to receive the must from such a centrifugal separator device with horizontal axis and being configured to carry out a second separating operation between the liquid part of the must and the respective solid residue or tank bottoms. The plant also includes, upstream of the centrifugal separator device with horizontal axis, at least one tank operatively connected to at least one device for feeding at least partially intact grape berries to the plant. The tank is arranged to contain additives, in particular adjuvant and/or clarifying substances, that are added to the grape berries when such grape berries are still at least partially intact. A method for obtaining clear must from grapes using the aforementioned plant is moreover described.

The present invention refers to a plant and to a vinification processor, more precisely, to a plant and to a process for obtaining clear mustor wine from grapes.

As known, vinification is the biochemical and technological process oftransforming grapes into wine and the refining thereof. In the case ofprocessing white wine and sometimes rosé wine, conventional proceduresof processing the grape for obtaining must to be sent to fermentationnormally foresee a first destemming and crushing step, which consists ofthe separation of the grapes from the stem, and a second pressing step,which allows most of the must present in the pulp of the grape berry tocome out.

Then there is a separation step of the solids (skin and seeds) and anextraction step of the must left in them. This operation is articulated,according to the conditions (pressure), into three steps that can beactuated by one or more machines:

-   1. draining, that consists of extracting the must from the solid    parts without applied pressure; it can be static or dynamic, as a    function of whether there is or is not movement of the crushed    grapes during the operation and, in in this last case, continuous or    discontinuous; the must obtained with this operation, with low    mechanical impact on the plant matrix, is good quality and is    defined “free-run must”; the draining operation can be carried out    by specific machines, or also during the first crushing steps, when    the extraction of the must continues without applying overpressure;-   2. pressing, which follows the draining and that consists of    extracting must from the solid parts with the limited aid of    pressure (maximum 2-3 bars); also in this case the technologies can    be continuous or discontinuous; the latter, especially if of the    pneumatic type, are more suitable for obtaining high quality must;    the first fractions of must obtained at low pressure are still    considered “free-run must”, whereas the following fractions,    constitute the “press-must”, which are generally intended for the    production of low/average quality wines;-   3. screw-pressing, which follows the pressing and that consists of    extracting the residual must that is present in the solid parts with    the aid of higher pressure; the musts thus obtained (“last presses”)    are generally intended for the production of semi-finished goods    such as “sulfited musts” so as to then be transformed into RCM    (acronym of “rectified concentrated must”).

These separation/extraction technologies of the must are also used inprocessing red wines for separating the must, after hot maceration, andfor separating wine, after fermentation carried out in the presence ofsolid parts (skin and seeds).

The must thus obtained can undergo a possible step of sediment removal,i.e. the separation of the particulate present in the must, such as toallow a clear must to be obtained with values of turbidity that areindicatively lower than 200-300 NTU (Nephelometric Turbidity Units), orin any case lower than 1.5% by weight of solids in suspension,considered optimal for the production of good quality white wines. Themethods foreseen for removing the sediment are generally sedimentationand flotation, static or dynamic, or less frequently filtration withrotary vacuum filters and centrifugation. The sediment removal operationcan be helped with the use of enzymes and/or clarifying substances. Inthe case of sedimentation and of flotation, the must contained in thesediment is further separated with systems that are suitable foroperating with high solid content (press filters, vacuum rotary filters,decanters, etc.).

In some cases, in the production of white and rosé wines, suchoperations are preceded by a maceration step so-called “skin contact”,carried out also at temperatures that are lower than room temperature(cold maceration or cryo-maceration). The clear must in any caseobtained is thus intended for alcoholic fermentation, in general managedat a controlled temperature.

In the case of the production of red wines it is always foreseen forthere to be, after the destemming and the pressing, a maceration stepthat can be simultaneous to the fermentation (traditional redvinification), or it can be separated and prior to the alcoholicfermentation (thermovinification, “flash detente” and variants thereof,carbonic maceration or yet more). Then, in the case of the production ofred wines, the separation of the solid parts (skin and seeds) can becarried out before the fermentation in the case in which there has beensome sort of maceration of the grape, or after alcoholic fermentation(vinification in traditional red): said separation is obtained withmachines and technologies that are the same as those described forseparating/extracting the must for the production of white wines.

All wines, white and red, after alcoholic fermentation require one ormore settling operations, often operating with settling in tank andpossibly with the addition of clarifying substances. The lees (sediment)is further filtered with special filters (plate or vacuum filters), orthrough disc centrifuges or continuous centrifuges with horizontal axis,called decanters. From this operation a “wine from lees” and semi-solidlees are obtained intended for distillation.

Vinification processes of the known type described above usually requireplants in which it is necessary to manage and control numerous machinesand technologies that are different from one another. Vinificationplants of the known type are disclosed, for example, in documents CH 622820 A5 and WO 91/05847 A1. Specifically, the separation/extractionprocesses of the must (draining and pressing) are complex, costly,require high labour for managing and cleaning and are alwayscharacterised by long process time, which clash with the essentialcriterion for obtaining must that is suitable for producing high qualitywhite wines, that is to say that of a rapid process dictated by kineticsof the enzymatic reactions which are extremely efficient in thepre-fermentation step.

Moreover, certain separation steps of the process, like for examplefiltration, require long time in order to be carried out, the use ofspecialised labour, the use of tanks and, in the case of filtration(dead-end, flooding), the use of filtration adjuvants (fossil meals andminerals). All this translates into having substantial management costs,logistic complexity, high water and energy consumption that jeopardisethe “sustainability of the wine”. Even the methods of separation throughsedimentation or flotation are characterised by similar criticalfactors, i.e. use of tanks and the washing and disinfection thereof,production of solid and liquid waste.

The vinification processes of the known type thus have a series ofproblems and of criticalities of various nature: management of space andlogistics, high production costs and high costs for managing the variousprocesses, environmental impact both due to the large amount of waterused for washing the tanks and of the production lines, and to thenecessity of disposing of the adjuvants used in the filtration andclarification steps.

In addition, the most recent and increasingly more widespread methods ofmechanically picking the grapes, which are rapid and efficient and thatmake it possible to obtain grape berries that are already without theirstems, require vinification plants and processes that are just as rapidand efficient in order for the entire production chain to be correctlybalanced, as well as rapidity in the processes dictated by kinetics ofthe enzymatic reactions that are responsible for the deterioration interms of quality of the must, especially in the case of processing whitewines, the quality of which is strongly conditioned by thepre-fermentation operations. This objective is not always achieved withconventional plants and processes for obtaining must from the grape.

The purpose of the present invention is therefore that of making avinification plant and a process or more precisely, a plant and aprocess for obtaining clear must from grapes, that are capable ofsolving the drawbacks mentioned above of the prior art in an extremelysimple, rapid, cost-effective and particularly functional manner.

In detail, one purpose of the present invention is that of making aplant and a process for obtaining clear must from grapes that arecapable of reducing the number of processes and the amount of machineryused to carry out such processes, so that the plant and the productionline are more compact and efficient with respect to conventional ones.

Another purpose of the present invention is that of making a plant and aprocess for obtaining clear must from grapes that are capable ofreducing the consumption of water and of chemical substances andadjuvants used in the various processing steps, therefore leading to alower environmental impact.

These purposes according to the present invention are achieved by makinga vinification plant and process or, more precisely, a plant forobtaining clear must from grapes as outlined in the independent claims.

Further characteristics of the invention are highlighted by thedependent claims, which are an integrating part of the presentdescription.

In brief, the process for obtaining clear must from grapes according tothe present invention proposes to obtain, continuously and in a singlefundamental processing step, starting from grape berries that arealready destemmed or from bunches of grapes that are obtained throughmanual or mechanical picking methods, a must having a turbidity that isnot greater than 200-300 NTU (Nephelometric Turbidity Units), or in anycase lower than 1.5% by weight of suspended solids, and a solid pressedpart consisting of the skin, seeds, the turbid material separated fromthe must and the adjuvants used for the process. The plant according tothe present invention essentially operates by means of a centrifugeseparator with horizontal axis (decanter), as illustrated for example inthe document of the prior art U.S. Pat. No. 5,656,180, but it isintegrated with specific equipment for homogenizing and dosingadjuvants, which operate before the centrifuge treatment and thatdetermine in a fundamental manner the performance of such a decantercentrifuge separator and of the step of clarifying through flocculation.

In all the pilot experiences it has indeed been demonstrated that theessential factors for obtaining a correct efficiency of the centrifugeprocess is to supply the centrifuge separator with horizontal axis(decanter) with a homogeneous mass of solids and liquid. It has alsobeen demonstrated that obtaining a must that is separated with a levelof limpidity that is lower than 200-300 NTU can be obtained exclusivelyif the product has undergone pre-emptive enzymatic action and,especially, if suitable doses of clarifying adjuvants are dosed beforecentrifugation.

Using clarification is well known and traditional in winemakingprocesses by using clarifying substances of different nature: animalproteins (for example: gelatine derived from cows or pigs, fishgelatine, casein, egg albumin) and more recently plants, mineralclarifying substances (for example: bentonite, silica sol and silicagel) and others. Their characteristics and their behaviour have been theobject of studies in the past. The most recent studies (Ferrarini R. etal., “Importance des charges électriques superficielles des adjuvantsænologiques des particules et des colloïdes presents dans les moûts etles vins”, Revue Française d'œnologie—Cahier Scientifique, 158, 1-10,1996; Ferrarini R. et al., “Messa a punto di metodi per la valutazionemediante streaming current detector delle cariche elettrichesuperficiali delle particelle e dei colloidi di interesse enologico”,2nd National Congress on Food Chemistry, Giardini Naxos, 24-27 May 1995.Proceedings, 223-230, 1995) have highlighted the importance of theirelectric charge in the processes of clarification through sedimentationand flotation (Ferrarini R. et al., “Recent advances in the process offlotation applied to the clarification of grape must”, Journal Of WineResearch, 6 (1), 19-33, 1995). However, their use has always beenstudied and applied exclusively in processes of clarification of mustsand wines and has never been the object of study let alone of winepractice in treating directly the whole grape and/or after beingpressed, that is to say on a means containing must and the solid partsof the grape (skin and seeds). This element is innovative and essentialfor obtaining the purposes of the present invention.

The characteristics and the advantages of a plant and of a process forobtaining clear must from grapes according to the present inventionshall become clearer from the following description, given as an exampleand not for limiting purposes, with reference to the attached schematicdrawings in which the single FIGURE is a schematic view of the maincomponents of such a plant.

With reference to the FIGURE, this shows a plant for obtaining clearmust from grapes according to the present invention, wholly indicatedwith reference numeral 10. The plant 10 is essentially made up of atleast one centrifugal separator device with horizontal axis or decanter12 that carries out a first separating operation, through application ofa centrifugal force, between the liquid phase or must and the solidphase from the grape berries. The centrifugal separator device 12 canindeed be configured so as to directly receive the grape berries withoutstems. In case of the processing of grapes picked manually, the plantcan be provided, upstream of the centrifugal separator device 12, of aspecial device 14 for destemming or crushing capable of separating thegrapes from the relative stem and possibly press them. The solidsextracted from the centrifugal separator device 12 are expelled from theplant 10 and can be treated according to procedures of the known type.

The plant 10 also comprises, downstream of the centrifugal separatordevice 12, at least one tank for stating settling and/or flotation 16that receives the must from such a centrifugal separator device 12 andin which there is possibly a second separating operation between theliquid part of the must and the respective solid residue or tankbottoms. This second separating operation can be spontaneous, or it canbe facilitated by using gas (nitrogen or air) injected and dissolved inline before the tank for settling and/or flotation 16 through suitablesystems, one of which is described in greater detail hereafter. In sucha way it is simple to easily induce a subsequent separation of theresidual solids through flotation and/or partial sedimentation. Themust, possibly clarified by means of a production step that shall bedescribed in greater detail in the rest of the description, is sent tospecial fermentation tanks (not shown), whereas the solid residue orsediment is expelled from the plant 10 so as to possibly undergo knowntypes of treatment.

According to the invention, the plant 10 comprises, upstream of thecentrifugal separator device 12, at least one tank 18 operativelyconnected to at least one device 22 for feeding at least partiallyintact grape berries to said plant 10. Said at least one tank 18contains additives that are added to the grape berries when such grapeberries are still at least partially intact. In particular, theseadditives are made up of adjuvant and/or clarifying substances andpossibly also of enzymes. As an alternative, the enzymes (pectolyticenzymes) can be added also in previous processing steps, like forexample during mechanical picking. This intervention is known and isoften used in conventional grape processing. On the contrary, in plantsand in processes known to this day, the clarifying substances (like forexample gelatine, proteins, bentonite, silica gel or silica sol andothers) are added only to the liquid phases (must or wine).

In detail, the tank 18 comprises a first container 18A containing theenzymes, which is operatively connected to a homogenizer device 20 thatis arranged between such a tank 18 and the centrifugal separator device12. Inside the homogenizer device 20 there is thus an addition operationof such enzymes in the product made up of grape berries that are atleast partially “crushed” and of a must liquid fraction. As previouslymentioned, the enzymes could also be added to the grape berries beforethey are introduced inside the homogenizer device 20, as illustrated inthe FIGURE.

The tank 18 also comprises at least one other container 18B containingthe adjuvant and/or clarifying substances, in particular made up ofgelatine, proteins or cationic flocculants, which are added to the grapeberries after they have come out from the homogenizer device 20 andbefore they have entered the centrifugal separator device 12.

The process for obtaining clear must from grapes according to thepresent invention is thus carried out according to the following steps.After a preliminary step of feeding the grape berries, which may or maynot be destemmed, into the plant 10, there is a step of controlledaddition of enzymes, which are dispensed from the first container 18A,to such grape berries while they are still in their solid phase. Thereis then a further step of controlled addition of adjuvant and/orclarifying substances, which are dispensed from the second container18B, to the grape berries themselves while they are still at leastpartially intact.

The grape berries now with additives subsequently undergo a step ofcentrifugation in the centrifugal separator device 12, in such a way asto separate the liquid phase or must from the solid phase and the turbidflocculated substance by means of the specific clarifying substancesused. Both the must, and the solids are thus extracted and collected inrespective storing recipients.

The liquid part of the clarified must is finally sent to the finalfermentation step without it being necessary for there to be furtherprocessing steps. As an alternative, the must can be further and moreeasily clarified with other conventional processes (sedimentation,flotation, filtration, centrifugation). Again as an alternative, themust may not be intended for fermentation but rather for the productionof juices or other non-fermented semi-finished products. The finalresult of the process according to the present invention indeed consistsof a must that is already clarified and of a quality that is at leastthe same as that of a must which could be obtained with conventionalprocesses. With the process according to the present invention it ismoreover possible to drastically reduce the amount of sediment that isseparated through sedimentation and/or flotation in the special tank 16with respect to what occurs in conventional processes, making itpossible to even recover the must from such a tank for settling and/orflotation 16 through the centrifugal separator device 12.

Before the final fermentation step the operations carried out on thecrushed grapes (white or rosé) in the vinification step promote theoxygenation of the must and can lead to its oxidation. The control ofthis oxygenation allows oxidative phenomena to be reduced and thereforeallows the negative impact on the chemicals of the wine and,consequently, on its aromatic intensity, to be limited, while it ensuresan improvement in the stability of the wine itself.

The process for obtaining clear must from grapes according to thepresent invention makes it possible to drastically shorten the times andthe number of operations to obtain the desired level of clarification.Such shortness and simplicity of the process offers the possibility ofcontrolling the level of oxygenation as required by using gas (normallynitrogen) in the centrifugal extraction step and in the step immediatelyafter.

The process foresees to inject the inert gas, directly together with thecrushed grapes, in inlet to the centrifugal separator device 12, inpredetermined points outside of such a centrifugal separator device 12and close to the outlet point of the clarified must (see FIGURE).Through this injection of inert gas it is possible to reduce theoxygenation of the must up to over 60%. The remaining oxygen, which mayhave been transferred to the must in the centrifugal extraction step, issubjected to stripping with the help of a gas mixer 24, arranged betweenthe centrifugal separator device 12 and the tank for settling and/orflotation 16.

It has thus been seen that the plant and the process for obtaining clearmust from grapes according to the present invention obtain the purposesthat were previously highlighted. Actually, the plant and the processaccording to the present invention can substitute traditional plantsprovided with press and clarification machinery (filtration, flotationor centrifugation), eliminating the equipment and the auxiliary steps(storing in the tanks, manipulations and pauses, filtration of the tankbottoms, must cooling, etc.). In addition, in the case in which thegrape is picked mechanically, even the furtherdestemming/crushing-destemming and homogenisation step can beeliminated.

The advantages of the plant and of the process according to the presentinvention can thus be summarised as follows: cutting down of the cost,lower environmental impact (high sustainability), advantages in theproduction processes of the grape coming from mechanical grape harvest(quick production in a single step, possible elimination of thedestemming/crushing-destemming device), greater yield, lower waterconsumption and lower use of cooling systems, due to the fact that theprocess substantially occurs at room temperature and that it is onlynecessary to cool the already clarified must.

The plant and the process for obtaining clear must from grapes of thepresent invention thus conceived can in any case undergo numerousmodifications and variants, all covered by the same inventive concept;moreover, all the details can be replaced by technically equivalentelements. In practice the materials used, as well as the shapes andsizes, may be any according to the technical requirements.

Finally, such a process with the suitable modifications and variants,but operating conceptually on the same principle, can be applied toseparate the solid parts of the grape (skin and seeds) after theoenological processes that foresee a maceration step of the white andred grapes: cold maceration, skin maceration, hot maceration, “flashdetente”, carbonic maceration, etc.

The scope of protection of the invention is thus defined in the attachedclaims.

1. A plant for obtaining clear must from grape berries comprising: atleast one centrifugal separator device with a horizontal axis that isarranged to carry out a first separating operation, through applicationof a centrifugal force, between a liquid phase or must and a solid phasefrom the grape berries when in a solid state; and at least one firsttank for settling and/or flotation, said at least one first tank beingarranged downstream of the at least one centrifugal separator device,said at least one first tank being configured to receive the must fromsaid at least one centrifugal separator device and being configured tocarry out a second separation operation between a liquid part and asolid residue of the must; and at least one second tank upstream of thecentrifugal separator device, said at least one second tank beingoperatively connected to at least one device for feeding at leastpartially intact grape berries to said plant, said at least one secondtank being arranged to contain additives that are added to the grapeberries when said grape berries are still at least partially intact. 2.The plant according to claim 1, wherein said additives comprise adjuvantand/or clarifying substances.
 3. The plant according to claim 2, whereinsaid adjuvant and/or clarifying substances are selected from the groupconsisting of gelatine, proteins and cationic flocculants.
 4. The plantaccording to claim 2, wherein said additives consist of enzymes.
 5. Theplant according to claim 4, wherein said at least one second tankcomprises a first container containing the enzymes.
 6. The plantaccording to claim 5, wherein the first container is operativelyconnected to a homogenizer device arranged between said at least onesecond tank and the at least one centrifugal separator device, whereinan addition operation of said enzymes to the grape berries while thegrape berries are still at least partially intact is carried out insidesaid homogenizer device.
 7. The plant according to claim 5, wherein saidat least one second tank further comprises at least one second containercontaining the adjuvant and/or clarifying substances, which are added tothe grape berries after the grape berries have come out from thehomogenizer device and before the grape berries have entered into the atleast one centrifugal separator device.
 8. The plant according to claim1, further comprising a destemming or crushing-destemming deviceupstream of the at least one centrifugal separator device, saiddestemming or crushing-destemming device being capable of separating thegrape berries from the stems or separating the grape berries from thestems and crushing the grape berries.
 9. The plant according to claim 1,further comprising a gas mixer arranged between the at least onecentrifugal separator device and the at least one first tank, said gasmixer being configured to strip oxygen from the must.
 10. A process forobtaining clear must from grape berries in the plant according to claim1, the process comprising the steps of: feeding the grape berries intothe plant; controlled addition of adjuvant and/or clarifying substancesto said grape berries while the grape berries are still at leastpartially intact; centrifuging said grape berries, in such a way as toseparate the liquid phase or must from the solid phase; extracting andcollecting the solid phase in a respective storage container; andsettling and/or flotation of the liquid phase or must so that the liquidphase of said must and the solid residue are separated.
 11. The processaccording to claim 10, wherein said adjuvant and/or clarifyingsubstances are selected from the group consisting of gelatine, proteinsand cationic flocculants.
 12. The process according to claim 10, furthercomprising the step of controlled addition of enzymes to the grapeberries while the grape berries are still at least partially intact,said step of controlled addition of enzymes being upstream of the stepof controlled addition of adjuvant and/or clarifying substances to thegrape berries.
 13. The process according to claim 10, further comprisingthe step of destemming or crushing-destemming to separate said grapeberries from the stem or to separate the grape berries from the stem andpress crush the grape berries, said step of destemming orcrushing-destemming being upstream of the step of controlled addition ofadjuvant and/or clarifying substances to the grape berries.
 14. Theprocess according to claim 10, further comprising the step of fermentingsaid must, said step of fermenting being downstream of the settlingand/or flotation step of the liquid phase or must.
 15. The processaccording to claim 10, wherein the process is applied in the separationof the solid parts of the grape berries (skin and seeds) after theoenological processes that foresee a maceration step of white and redgrapes.
 16. The plant according to claim 1, wherein the at least onefirst tank for settling and/or flotation operates spontaneously or ispromoted through injection of gas.
 17. The plant according to claim 3,wherein said additives consist of enzymes.
 18. The plant according toclaim 6, wherein said at least one second tank further comprises atleast one second container containing the adjuvant and/or clarifyingsubstances, which are added to the grape berries after the grape berrieshave come out from the homogenizer device and before the grape berrieshave entered into the at least one centrifugal separator device.
 19. Theplant according to claim 2, further comprising a destemming orcrushing-destemming device upstream of the at least one centrifugalseparator device, said destemming or crushing-destemming device beingcapable of separating the grape berries from the stems or separating thegrape berries from the stems and crushing the grape berries.
 20. Theplant according to claim 3, further comprising a destemming orcrushing-destemming device upstream of the at least one centrifugalseparator device, said destemming or crushing-destemming device beingcapable of separating the grape berries from the stems or separating thegrape berries from the stems and crushing the grape berries.